On the one hand, this invention relates to a three-position shed-forming device, comprising a shed-forming element provided to be attached at at least one warp yarn on a weaving machine, one set of lifting means with a first and a second lifting means, which are movable up and down over a different lifting height respectively, and a selection device to selectively influence the shed-forming element, so that it may be carried along or not by a lifting means of the set.
On the other hand, this invention relates to a three-position shed-forming device, comprising two shed-forming elements, pulley block device provided for to transmit the movements of both shed-forming elements to at least one warp yarn on a weaving machine, a set of lifting means with a first and a second lifting means, which are movable up and down over a different lifting height respectively, and a selection device, by means of which each shed-forming element may be influenced selectively, so that it may be carried along or not by a lifting means of the set.
This invention more particularly relates to a three-position-jacquard machine, that is provided with a number of the shed-forming devices, indicated in the first and/or second paragraph in order to form a shed between the warp yarns, during the successive working cycles of the weaving machine, each warp yarn each time being brought into such a position with respect to the path of movement of the weft insertion means of the weaving machine, that these warp yarns and the weft yarns inserted into the shed form the fabric desired, according to the given weaving pattern.
With a three-position-jacquard machine the warp yarns may be brought into three possible positions. Moreover, if all these three positions may be realized at each weft insertion on the weaving machine (this means after each half cycle of movement of the blades), regardless of the previous position, this jacquard machine functions according to the open-shed principle.
In this patent application, the three different positions of the warp yarns are indicated as the upper, center and lower positions.
In the German patent DE 41 01 778 C1 a three-position-jacquard machine is described with shed-forming systems with two hooks working together, which are interconnected by means of a pulley block cord and a pulley block suspended in the down hanging loop of the pulley block cord, which is connected to one or more warp yarns via a harness cord. On selection, each hook may be carried along by a blade moving up and down. Two hooks working together are working together with blades moving in opposite phase respectively.
This machine has three-position shed-forming devices of which two of the hooks working together, when selected, are carried along by blades with a different lifting height respectively. By selecting one hook or the other of a pair of hooks working together the warp yarns may be brought into a center or an upper position via the pulley block. When none of the two hooks is selected, the warp yarns connected to the pulley block remain in their lower position, resting on the bottom plank. With these shed-forming devices the three different positions of the warp yarns cannot be reached after each half cycle of movement of the blades. If the blade with the highest lifting height is in its top dead center the upper or lower positions may be reached. If the other blade is in its top dead center the center of lower positions may be reached.
These shed-forming devices have the disadvantage that it is not possible to realize each of the xe2x80x9cupperxe2x80x9d, xe2x80x9ccenterxe2x80x9d or xe2x80x9clowerxe2x80x9d positions, after having realized the xe2x80x9clowerxe2x80x9d position after the next half cycle of movement of the blades. Another disadvantage of these shed-forming devices is, that they comprise a pulley block with a pulley block cord. The pulley block cords of a jacquard machine are subject to severe wear because of the friction among them. Moreover, replacing the pulley block cords is time consuming and causes fairly long machine stops.
The jacquard machine from DE-4101778C1 also has three-position shed-forming devices, the two co-operating hooks of which may be carried along by a first and a second blade respectively, each having a same lifting height. The first blade has two hooking on elements provided at a different height, whereas the second blade has only one hooking on element at the level of the upper hooking on element of the first blade. The upper hooking on element is situated near the curved upper extremity of a hook resting on the bottom plank when the first blade is in its bottom dead center. The lower hooking on element is then at a considerably lower level. Therefore one hook is lifted less high when it is carried along by the lower hooking on element than in case when it is carried along by the upper hooking on element. Therefore, depending on the hooking on element chosen, a hook may be brought into two different heights by the first blade, in order to bring the warp yarns in a center position or an upper position. The lower position is realized when both hooks remain in their lowest position on the bottom plank.
Also with these three-position shed-forming devices, the three different positions of the warp yarns cannot be reached after each half cycle of movement of the blades. When the second blade (with one hooking on element) is in its top dead center, only the xe2x80x9cupperxe2x80x9d and xe2x80x9clowerxe2x80x9d positions may be reached, when the first blade (with two hooking on elements) is in its top dead center however, the three positions xe2x80x9cupperxe2x80x9d, xe2x80x9ccenterxe2x80x9d and xe2x80x9clowerxe2x80x9d may be reached.
However, these shed-forming devices present the disadvantage that two controls of the selection device are needed, following each other very quickly, in order to select a hook in such a manner, that it is carried along by the lower hooking on element. A first control of the selection device is needed to bring the hook outside the carrier range of the upper hooking on element. A very short time thereafter, when the blade has been lifted a little, a second control of the selection device is needed to bring the hook within the carrier range of the lower hooking on element. These double controls are causing a considerable consumption of energy. The provisions for the energy supply must, of course, be adapted to that high consumption.
A second disadvantage is, that the hooks which are carried along by a lower hooking on element, are picked up by rising blades which are already fairly high above their bottom dead center and therefore are already in full movement. The non too soft contacts between the lower hooking on elements and the hooks will cause shocks in the jacquard machine as a result of which no high weaving speed can be obtained.
A first objective of this invention is to realize a three-position shed-forming device of the type with which it will be possible to realize each of the xe2x80x9cupperxe2x80x9d, xe2x80x9ccenterxe2x80x9d or xe2x80x9clowerxe2x80x9d positions after having realized the xe2x80x9clowerxe2x80x9d position for the warp yarns, after the next half cycle of movement of the blades, but without the disadvantages mentioned above of the known jacquard machines, more particularly without the use of pulley block elements and with the possibility to realize each position by only one control of a selection element. A further part of this objective is also to provide for a device with which a three-position open-shed-jacquard machine may be composed, using only one pulley block element.
A known three-position open-shed-jacquard machine is described in the European patent EP 0 399 930. In this jacquard machine each shed-forming device has two pairs of hooks. The hooks of each pair may be carried along by blades moving up and down respectively, after they have been brought into a carrier position by a selection device. The blades working together with a pair of hooks are movable in opposite phase. The hooks of each pair are interconnected by a first and a second pulley block cord respectively which, between the hooks, are passed round under the upper pulley block of a respective pulley block element with an upper and a lower pulley block. A third pulley block cord is attached to one of the extremities in a fixed point and with the other extremity it is connected to a harness cord, which has been provided to determine the position of a warp yarn. From the firmly connected extremity, the third pulley block cord passes over the lower pulley block of the one pulley block element, under a firmly arranged reversing pulley and over the lower pulley block of the other pulley block element successively.
So, in order to bring a warp yarn into three different positions, two pairs of hooks, arranged next to each other with corresponding selection elements are needed. A similar shed-forming device has the disadvantage that it takes up a lot of space. Another disadvantage consists in the fact that for each shed-forming device two selection elements must be controlled, entailing a considerable consumption of energy. Of course, the provisions for the energy supply should be adapted to these circumstances. Moreover each shed-forming device needs three pulley block cords being subject to wear in consequence of the friction among them. The great number of different components (two pulley block elements, a reversing pulley, two selection systems, four hooks) makes this shed-forming device rather complex and expensive.
The device according to EP 0 839 937 is a three-position shed-forming device which takes up less space than the device according to EP 399 930, because four hooks may be carried along two by two by a respective blade and because each hook may be selected by a common selecting element disposed between the pairs of hooks. However, this shed-forming device still requires two pulley block elements and a reversing pulley as well as a number of pulley block cords subject to wear. Moreover, in this case also two selection elements must be controlled.
A second objective of this invention is to provide likewise for a three-position shed-forming device of the type that is able to function according to the open-shed principle, with which the above-mentioned disadvantages of the known three-position open-shed shed-forming device are remedied and which, more particularly, comprises less pulley block elements than the known devices, as for each position only one single control is required.
The objectives mentioned above are obtained by applying the same inventive idea, that consists in making each shed-forming element of the existing devices work together with a first and a second lifting means moving in phase with a different lifting height, and in making it ready to be selected to be carried along by either the one lifting means, or by the other lifting means, or by none of the lifting means at all.
The first objective mentioned above is obtained by carrying out the three-position shed-forming device, with the characteristics mentioned in the first paragraph of this description, in such a manner, that the shed-forming element may be influenced selectively to be carried along either by a first lifting means, or by a second lifting means, and that the first and the second lifting means are movable in phase.
Therefore, the shed-forming element, in each moving cycle of the blades, may be kept either in the lower position or may be brought at a first height by the one lifting means, or may be brought at a second height by the other lifting means. If the shed-forming element is directly connected to a harness cord that, in its turn, is able to position a warp yarn, then this warp yarn may be brought also into three different positions. However, these positions cannot be realized after each half cycle of movement. If the lifting means are in their bottom dead center, only the lower position is realizable. If the lifting means are in their top dead center, each of the three positions may be realized. A similar shed-forming device has not a single pulley block element and therefore no pulley block cords.
Each shed-forming element may be subjected to two selections, resulting in a center position and an upper position respectively. Each selection results in the shed-forming element being carried along by a different lifting means and may therefore be easily realized by two selection means separated from each other. If a different selection element is provided for each selection, then only one single control of the selection element is required for each position. This shed-forming device may be realized in a particularly simple and compact manner and allows for a quick and shock-free operation. As will appear from the following, his shed-forming device may also be used to compose a three-position open-shed shed-forming device, using only one single pulley block element.
According to the invention, the above-mentioned second objective is obtained by applying the same inventive idea, and results in a three-position shed-forming device, having the characteristics mentioned in the second paragraph of this description, in which, for each of the two shed forming-elements a respective set of lifting means with a first and a second lifting means movable in phase is provided for, the lifting means of the one set and the lifting means of the other set being movable in opposition with respect to each other, and each shed-forming element may also be influenced selectively in order to be carried along either by the first lifting means, or by the second lifting means.
A similar shed-forming device allows for a warp yarn on a weaving machine to be brought into each of the three positions after each half cycle of movement of the blades. Each time, one of the sets lifting means is in its top dead center (i.e. after each half cycle of movement) a shed-forming element may be brought at three different heights at will. Because both shed-forming elements together determine the positions of the warp yarns, therefore three different positions of a warp yarn may be realized after each half cycle of movement. This shed-forming device functions according to the open-shed principle and requires only one pair of shed-forming elements, so that it takes up little space (one division) and it has only one pulley block element. This shed-forming device may be built in a compact manner.
Here also, each shed-forming element may be submitted to two different selections, resulting in a center position and an upper position respectively. Each selection results in a shed forming-element, carried along by a different lifting means and may therefore be easily realized by selection means, separated from each other. If for each selection a different selection element is provided, only one single control of a selection element is required for each position. Therefore, this device will consume only little electric energy.
In the most preferred embodiment of the above-mentioned three-position open-shed shed-forming device, the two shed-forming elements are interconnected by a first pulley block cord which, between both shed-forming elements, is passed under the upper pulley block of a pulley block element with two pulley blocks, whereas a second pulley block cord is passed over the lower pulley block of the pulley block element and, on the one hand, is connected to a fixed point with respect to this lower pulley block and, on the other hand, is provided to be connected to one or more warp yarns of a weaving device.
In a preferred embodiment of the shed-forming devices according to this invention the first and the second lifting means of each set comprise a first and a second carrier means respectively, to carry along a shed-forming element, whereas the difference in height between this first and second carrier means is smaller than the difference between the lifting heights of the lifting means, when these lifting means are in their bottom dead center.
As the difference in height between the first and second carrier means (in the bottom dead center of the lifting means) defines the minimal length of the shed-forming elements working together with these lifting means, this characteristic allows for the use of fairly short shed-forming elements. Because of this, the device may be carried out with great compactness, also as to height.
Preferably, each lifting means is provided to carry along the shed-forming element situated in a lower position to an upper position from a height almost coinciding with the bottom dead center of the lifting means concerned. Because of this a shed-forming element is carried along from the beginning of the movement of the lifting means. Because of this the first contact between the lifting means and the shed-forming element passes off without shocks or vibrations. Because of this a quick, efficient shed-forming device is obtained.
If the first and the second lifting means are situated one below the other during their up and down going movement, the device may be built in a very compact manner as to width. Preferably, the first and second lifting means of each pair are situated in a same vertical plane one below the other during their up and down going movement.
Preferably, the lifting height of the first lifting means is almost double the lifting height of the second lifting means. Because of this, the intermediate distance between the upper and the center position of each shed-forming element is almost equal to the intermediate distance between their center and their lower position.
Preferably, the shed-forming devices according to the invention are carried out in such a manner that the selection device may be controlled selectively in order to place a first selection body either in a carrier position, where the shed-forming element may only be carried along by the first lifting means, or in a non-carrier position, where none of the lifting means will be able to carry along the shed-forming element, whereas the selection device may also be controlled selectively in order to place a selection body either in a carrier position, where the shed-forming element may only be carried along by the second lifting means, or in a non-carrier position where none of the lifting means will be able to carry along the shed-forming element.
According to a most preferred embodiment of the devices according to this invention the first and second selection body are part of the shed-forming element. Moreover, these selection bodies are preferably carried out as swivel catches, which may be placed in two different positions by means of an actuator of the selection device, a carrier position and a non-carrier position. Preferably, these shed-forming elements and/or these actuators are carried out as described in the Belgian patent application number 2000/0679.
In a very advantageous embodiment the two positions of each selection body are stable positions.
In an embodiment where the selection device for each selection body comprises an actuator, one single control is enough to select the-shed forming element and this is the case for each position to be realized.
This device is carried out with the greatest possible compactness and with a minimum of parts when it comprises a series of shed-forming elements which are arranged in several rows next to each other, while the selection devices working together with the shed-forming elements of two rows situated next to each other are disposed between these rows, and while a first and a second lifting means is provided between the rows where no selection devices are provided in order to carry along shed-forming elements of both these rows. In that manner each set of lifting means will be able to work together with two rows of hooks, while the selection devices of two rows of hooks are disposed back to back between these rows.
Preferably the selection devices working together with a number of shed-forming elements of two rows situated next to each other are incorporated in a same selection unit. Preferably a similar selection unit is carried out as a separate removable entity.
Now this invention will be further explained by means of the following detailed description of two preferred three-position shed-forming devices according to this invention and of their functioning. The sole intention of this description is to further elucidate the invention by means of an example and to indicate its further advantages and particularities and it should therefore in no way be interpreted as a limitation of the field of application of the invention or of the patent rights claimed in the claims.